My research interests focus on ancient ultramafic mantle melts and the products of their formation – both residues left behind in their mantle source regions and differentiation products such as ultramafic cumulates and basalts in the Earth’s crust. My PhD research centered on the ca. 1.9 Ga Winnipegosis Komatiites from Manitoba, Canada, some of the best preserved komatiites in the world and a rare example of Proterozoic komatiite magmatism. Following this, I completed a post-doc with the Metal Earth project, attempting to understand the genesis of precious metal deposits by studying mantle samples from beneath an active gold mine. Alongside these major research works, I have participated in a variety of projects, including remote fieldwork in Northern Canada and Greenland, and research on the metamorphism of Archaean komatiites, precious metal mobility in Phanerozoic ophiolites, chromite provenance in Archaean sedimentary rocks, and even the origins of S-type granites. I use a variety of petrological and geochemical techniques, with a focus on platinum group element (PGE) geochemistry and Re-Os isotopes, supported by in-depth geochemical modelling. In January 2019, I began a post-doc at the University of Copenhagen, studying ultramafic dykes and enclaves in Archaean gneisses from West Greenland with a view to understanding their origins and relevance to lithosphere stabilisation in the North Atlantic Craton.

Jargon-free research interests

My research interests focus on the Earth’s mantle and the magmas that form when it melts. The mantle is the solid rocky portion of the Earth that extends from just below the crust (from a few kilometers to 90 km deep), to the Earth’s core roughly 2900 km below the surface. Under certain conditions this mantle rock can melt to form magma, and erupt as a lava. By studying some of the hottest lavas that erupted at different times in Earth history, my research seeks to capture ‘snapshots’ of the temperature and composition of the Earth’s mantle through time. More recently, I have worked on direct mantle samples, where chunks of mantle rock are brought to the surface, either through being ripped up and erupted in volcanoes, or thrust to the surface along geological faults. As a geochemist, I mainly study rocks by grinding them into a powder, dissolving them, and analysing their chemical composition with mass spectrometers. I particularly specialise in analysing precious metals related to platinum. These elements are very rare near the Earth’s surface but common in the Earth’s core and in meteorites, so they can tell us about the processes that formed the Earth’s core, or the last stages of Earth formation when the Earth and Moon were being bombarded by giant meteorites.

Archaean to Proterozoic noritic dykes in the Maniitsoq region have been interpreted as either arising from boninite-like melts formed by remelting of previously depleted mantle, or as the product of extensive crustal contamination of an ultramafic melt such as a komatiite or picrite. These different interpretations have profound implications for the geodynamic setting of the North Atlantic Craton at ~2.5 Ga; a boninite-like origin could imply the presence of a subduction zone, whereas a crustal contamination origin might imply the presence of a mantle plume or incipient rifting of the craton.

A compositionally similar series of ~3 Ga noritic intrusions also occurs in the Maniitsoq region, concentrated in a ~75 x 15 km curvilinear belt of noritic bodies hosted in TTG gneiss known as the 'Maniitsoq (or Greenland) Norite Belt'. They have previously been interpreted as magma conduits and intrusions generated by mantle melting in response to a giant impact, but both their relationship to their host gneisses and even the presence of a giant impact in the Maniitsoq region are disputed. These intrusions are locally mineralised and of great interest to the mining exploration industry; understanding their mode of formation is critically important to understanding their mineral potential.

Samples were collected during fieldwork in 2016 and 2017 as part of the Government of Greenland Maniitsoq 1:100000 map sheet project, with further samples and data provided by North American Nickel. In collaboration with researchers at a number of different universities, we are currently conducting an in-depth petrological, geochemical, and geochronological study of these samples to better understanding their mode of formation. Analytical approaches include: major-, trace-, and platinum group- element abundance analyses; EPMA mineral analyses; Lu-Hf, Sm-Nd, Re-Os, and O isotopic analyses; zircon and baddeleyite U-Pb dating; and detailed thermodynamic and trace element modelling.

Age and origin of the Ujaragssuit layered ultramafic intrusion: the oldest rocks on Earth?

The Ujaragssuit layered ultramafic intrusion is a dismembered ultramafic intrusion hosted in early Archaean TTG gneisses, located in the Ujaragssuit Nunat area, SW Greenland. The intrusion is dominated by metamorphosed dunites, but crucially preserves bands of chromitite which indicate primary igneous layering. Previous work has identified that the intrusion has an age > 3.8 Ga, and may be as old as 4.1 Ga, making it the oldest example of chromitite on Earth and a candidate for the oldest terrestrial rock.

Samples were collected during fieldwork in the summer of 2019, combined with small-scale mapping of the Ujaragssuit intrusion and its relationship with the surrounding gneisses. Following samples charaterisation and preliminary geochronological work, a number of standard and 'exotic' isotope systems will be applied to the samples to better establish their ages and place constraints on early Earth accretion and differentiation processes.